My son has a 2005 Audi A6 3.2 quattro I'm tryin g to work on. Car is running bad suddenly. seems to not go more then 20mph. I scanned it and its telling me cam position sensor bank 2. My question is how many CPS are there? Autozone claims there are 4 of them - Also where are they located exactly? Any help would be appreciated and thank you in advanced...